In recent qualitative studies, posttraumatic growth has been highlighted as a possible sign of change in how offenders relate to their basic existential needs. In this article, we present results of a pilot study with a mixed-method design on posttraumatic growth and psychological stress in a sample of sexual offenders (n = 30) in ongoing therapy. We performed univariate analyses and subsequent hierarchical analyses, and the results affirmed our hypothesis that posttraumatic growth is negatively associated with psychological stress. We used phenomenological analysis to identify themes in the participants’ reflections on posttraumatic growth. We found that prison experiences forced the participants to change. Prisoners experience emotional support from others during incarceration as crucial to positive change. Taking responsibility for the crime helped them engage in the therapy more fully and resulted in more posttraumatic growth.